The present invention is directed to a gas lift assembly for use in coiled tubing, and more particularly to a wireline retrievable, selective, flexible and spoolable gas lift valve for releasably seating in a selected mating coiled tubing housing.
Gas lift valves have long been used to inject lift gas into wells at selected depths for the purpose of forcing liquids, such as oil, to the surface of the well.
U.S. Pat. No. 5,170,815 discloses the use of a flexible gas lift assembly including a gas lift valve mounted within a coiled tubing. Such systems can replace expensive workover rigs. Such valves are permanently mounted within the internal diameter of the coiled tubing and have the advantage that the coiled tubing and valves are flexible and spoolable on the coiled tubing reel. However, such permanently mounted gas lift valves prevent through tubing wireline work, such as bottom hole pressure and temperature surveys, which are desirable. In such a system the entire coiled tubing must be pulled in order to perform downhole wireline work.
The present invention is directed to a coiled tubing retrievable and selective gas lift assembly in which the coiled tubing and gas lift valves are flexible and spoolable along with the coiled tubing, but the gas lift valves can be removed from the coiled tubing by wireline and may be reinstalled by wireline with each valve mating with a coacting and matching coiled tubing housing in a coiled tubing having a plurality of housing assemblies.